Quantum communication takes place when wave functions of quantum states travel from Alice to Bob through free space or fiber based channels [1]}. In physics, two waves are said to be coherent, if they maintain fixed phase relationship to each other or changes, according to the laws of physics, with time. Due to environmental effects and fragility of photons carrying the qubits, interaction of a the quantum states with the environment causes loss of photons, and hence the phase relationships are lost. This phenomena of loss of quantum information in environment with time is known as decoherence. Due to decoherence, quantum states looses its properties and enters the world of classical physics.
For preserving the quantum state of photons carrying the information, they must be perfectly-isolated from the environment, but this isolation is not practical and is hard to achieve, considering the current quantum technologies. Decoherence is irreversible and it affects the whole communication process including quantum teleportation process or entanglement generation and distribution process. Thus, decoherence is the main component that makes the quantum teleportation process imperfect and further degrades the fidelity of teleportation [2]}. Due to this phenomenon, the quantum states that were pure in nature are converted into mixed states [3]}.
